The Fischer-Tropsch process can be used for the conversion of synthesis gas into liquid and/or solid hydrocarbons. The synthesis gas may be obtained from hydrocarbonaceous feedstock in a process wherein the feedstock, e.g. natural gas, associated gas and/or coal-bed methane, heavy and/or residual oil fractions, coal, biomass, refuse is converted in a first step into a mixture of hydrogen and carbon monoxide. This mixture is often referred to as synthesis gas or syngas. The synthesis gas is then fed into a reactor where it is converted in one or more steps over a suitable catalyst at elevated temperature and pressure into paraffinic compounds and water in the actual Fischer-Tropsch process. The obtained paraffinic compounds range from methane to high molecular weight modules. The obtained high molecular weight modules can comprise up to 200 carbon atoms, or, under particular circumstances, even more carbon atoms. Numerous types of reactor systems have been developed for carrying out the Fischer-Tropsch reaction. For example, Fischer-Tropsch reactor systems include fixed bed reactors, especially multi-tubular fixed bed reactors, fluidised bed reactors, such as entrained fluidised bed reactors and fixed fluidised bed reactors, and slurry bed reactors such as three-phase slurry bubble columns and ebullated bed reactors.
Catalysts used in the Fischer-Tropsch synthesis often comprise a carrier-based support material and one or more metals from Group 8-10 of the Periodic Table of Elements, especially from the cobalt or iron groups, optionally in combination with one or more metal oxides and/or metals as promoters selected from zirconium, titanium, chromium, vanadium and manganese, especially manganese. Such catalysts are known in the art and have been described for example, in the specifications of WO 9700231A and U.S. Pat. No. 4,595,703.
Plants utilizing the Fischer-Tropsch process to convert syngas into long chain hydrocarbons are complex and comprise a large quantity of hardware. As the synthesis products consists of a variety of hydrocarbons having different carbon chain lengths starting methane to molecules having a chain length of more than 30 carbon atoms. Next to hydrocarbons water is a product of the Fischer-Tropsch synthesis. All these components exit the Fischer-Tropsch reactor in the effluent together with unconverted carbon monoxide and hydrogen and carbon dioxide. Typically, in order to remove the lighter Fischer-Tropsch hydrocarbons, H2O, CO and CO2 from the effluent one or more LES (light ends stripper) column is used. In order to remove these components the LES is operated at high temperatures requiring a lot of energy. Moreover the LES is a large column which are costly and complex to operate. This energy requirement and high costs weigh even heavier in case smaller plants are built. Further large and complex equipment takes up a lot of plot space and adds to the equipment count which is also disadvantageous.